1. Field of Invention
This invention relates generally to thermotherapy, and in particular to a thermotherapy technique and an instrument based thereon in which the heating medium in a preferred embodiment is a continuous stream of heated air projected at high velocity toward a skin surface area on the body of a patient in a pulsatory heat energy pattern causing rapid inward heat transfer to take place toward an internal problem region underlying this area in a manner raising the temperature of this region without, however, causing undue discomfort or injury to the patient.
2. Prior Art
The term "problem region" as used herein refers to a tumor, a set of muscles, or any other site underlying the skin which is causing difficulty and which lends itself to treatment by hot or cold therapy.
The interior of the human body has a normal temperature level which is usually said to be 98.6.degree. F. But actually, in the course of each 24-hour period, the body temperature rises above or falls somewhat below this nominal value. Body temperature is determined by the relationship existing between the amount of heat internally generated, which depends on basal metabolism and the amount of heat escaping from the body. Additional heat is produced as a result of muscular activity, this being dissipated by an increase in radiation, conduction or evaporation from the skin surface and by more rapid and deep breathing.
If the heat produced by a body surpasses heat losses therefrom, this gives rise to fever; but if heat losses exceed heat production, then the body temperature falls below the nominal value, resulting in shivering and hypothermia.
Medical practitioners since ancient times have known that the application of heat to the body is useful in the relief of muscle soreness and various aches and pains, as well as in the treatment of certain pathological conditions. Thus the use of heat for the treatment of arthritis and other abnormalities is now commonplace. Hot water bottles and electrical heating pads are in widespread use, not merely to provide warmth, but also to afford a degree of relief or therapy for various conditions. In applying heat to the surface of the body, one may do so by convection, by direct contact with a warmed substance; that is, by conduction, or by radiating energy into the body.
Difficulty has heretofore been experienced in effectively applying heat which is electrically or otherwise generated to a patient. When transferring heat inwardly through living tissue to a problem region underlying the skin, if the heat applied to the skin surface is within a tolerable temperature range, then not enough heat energy is transferred to this site to afford beneficial effects.
As pointed out in chapter 10, "Therapeutic Heat" in the text Therapeutic Heat and Cold, edited by Justus F. Lehmann and published in 1982 by Williams and Wilkins, it is generally accepted that heat produces desirable therapeutic effect, for it increases the extensibility of collagin tissues, it decreases joint stiffness, and it affords pain relief. Moreover, heat relieves muscular spasms, it aids in the resolution of inflammatory infiltrates, edema and exudates, and it enhances blood flow.
As indicated in the Lehmann text, superficial heat is commonly tied with various forms of heating media such as a paraffin bath, hot air or hot water and radiant heat (infrared). For a given patient, the temperature sensitivity threshold is that temperature level of the heating medium to which the patient is exposed, above which the patient experiences undue discomfort. Thus temperature levels of the medium below the sensitivity threshold are more or less tolerable, whereas those above the threshold are effectively intolerable. If, for example, a patient being subjected to thermotherapy finds that the heat is more than he can stand and wishes to procedure discontinued, clearly the heat of the medium to which he is exposed is above his sensitivity threshold.
One must bear in mind that the temperature sensitivity threshold is determined on the basis of continuous exposure to the heating medium, for one can tolerate much higher heat levels when one is only exposed momentarily or intermittently to high temperatures.
The temperature sensitivity threshold depends on the nature of the heating medium. Thus, as noted in the Lehmann text, when the medium is hot water which is at the same temperature and is applied to the patient in the same fashion as heated paraffin which has a low heat capacity, the paraffin can be tolerated by a patient but the hot water is intolerable for it has a high specific heat and a high order of thermal conductivity.
As a consequence, with conventional heating techniques, regardless of the medium used, when the patient is continuously exposed to a heating medium which is at a substantially constant temperature level, though this level is high enough to bring about adequate heat transfer to the problem region underlying the exposed skin, then the skin temperature is usually well above the tolerable level and this may result in extreme discomfort to the patient and even to the burning of tissue.
It is also now recognized that by heating tumors to a higher temperature than the surrounding tissue, the tumor may be caused to shrink and disappear. As noted in The New York Times of Apr. 14, 1982 (section C2) in an article on modern approaches to cancer treatment, the effectiveness of heat therapy is based on the fact that cancers have poor circulation and a reduced ability to dissipate heat. "Thus a temperature of more than 113 degrees Fahrenheit could destroy cancer cells while sparing normal tissue." The concern of the present invention is not with the heat treatment of any particular medical condition or problem region, but with a more effective technique therefor. Thus in the case of tumors, the practical problem encountered is that the surface temperature necessary to raise the tumor temperature to the proper level is intolerable.
While the present invention will be described mainly in connection with thermotherapy or hyperthermia, it is to be understood that a technique and apparatus in accordance with the invention is also applicable to hypothermia treatment in which therapeutic effects are gained by cooling an internal problem region.